Field of the Invention
The present invention relates to a contact device and
an electromagnetic relay using the contact device.
Background of the Invention
Conventionally, there is available a contact device in
which, as shown in Fig. 2, a movable contact point 51 is
held by a contact point retaining spring 71 formed of a leaf
spring and can be displaced with respect to a fixed contact
point 52 by the elastic deformation of the contact point
retaining spring 71 (see, e.g., Japanese Utility Model
Application Publication No. S63-37052). This contact device
is used in, e.g., an electromagnetic relay in which the
movable contact point 51 is driven by the magnetic force of
an electromagnet.
In this regard, if a large current flows between the
movable contact point 51 and the fixed contact point 52, a
repulsion force is generated between the movable contact
point 51 and the fixed contact point 52. For example, if a
large current flows in the direction indicated by arrows A3
in Fig. 2 (namely, from the fixed contact point 52 toward
the movable contact point 51) , the electromagnetic force
generated by the electric current flowing into a contact
region 50 of the fixed contact point 52 as indicated by
arrows A4 and the electric current flowing out of a contact
region 50 of the movable contact point 51 as indicated by
arrows A5 acts as a repulsion force by which the movable
contact point 51 is moved away from the fixed contact point
52 as indicated by an arrow A6. If the repulsion force is
larger than the spring force of the contact point retaining
spring 71, there may possibly occur opening of the contact
points (namely, separation of the movable contact point 51
from the fixed contact point 52).
In the event that arc discharge is generated between
the movable contact point 51 and the fixed contact point 52
during the opening of the contact points, there is a
possibility that the movable contact point 51 and the fixed
contact point 52 are welded together by the heat resulting
from the arc discharge.
Summary of the Invention
In view of the above, the present invention provides a
contact device capable of restraining opening of contact
points which may be caused by a large current and an
electromagnetic relay using the contact device.
In accordance with an aspect of the present invention,
there is provided a contact device, including: a contact
point retainer configured to hold a movable contact point in
one end portion thereof, the contact point retainer
including a plurality of contact point retaining springs
superimposed in a thickness direction and formed of leaf
springs; and a housing configured to fix the other end
portion of the contact point retainer and hold a fixed
contact point in a position where the movable contact point
can come into contact with or out of contact with the fixed
contact point in response to elastic deformation of the
contact point retainer, wherein each of the contact point
retaining springs includes a bulging portion swelling away
in a direction parallel or substantially parallel to a
direction from the movable contact point and toward the
fixed contact point.
A gap may exist between the bulging portion of at last
one of the contact point retaining springs and the bulging
portion of the contact point retaining spring adjoining to
said at least one of the contact point retaining springs.
The bulging portion may include a plurality of flat
sections connected to one another through angularly bent
sections.
The bulging portion may include upper and lower
sections extending parallel to each other.
The device described above may further include a
terminal plate electrically connected to the fixed contact
point and held in the housing in such a fashion as to
partially protrude outside the housing, the bulging portion
positioned near the terminal plate.
An electromagnetic relay may include the contact device
described above; an electromagnet stored and held within
the housing; and an armature stored within the housing
and driven by a magnetic force of the electromagnet,
wherein the movable contact point is configured to move
together with the armature and to come into contact with or
out of contact with the fixed contact point.
With the present embodiment, when a large current
flows, the repulsion force generated between one end and the
other end of the bulging portion acts to deform the contact
point retaining spring in such a direction as to press the
movable contact point against the fixed contact point. It
is therefore possible to restrain opening of the contact
points.
Brief Description of the Drawings
The objects and features of the present invention will
become apparent from the following description of
embodiments, given in conjunction with the accompanying
drawings, in which:
Fig. 1 is a front view showing an electromagnetic
relay according to one embodiment of the present invention,
with a cover removed for clarity; and
Fig. 2 is an explanatory view illustrating a problem'
to be solved by the present invention.
Detailed Description of the Preferred Embodiments
Hereinafter, one preferred embodiment of the present
invention will now be described in detail with reference to
the accompanying drawings which form a part hereof.
As shown in Fig. 1, an electromagnetic relay 100
according to the present embodiment includes an
electromagnet 1, an armature 2 rotationally driven by the
magnetic force of the electromagnet 1 and a housing 3 for
accommodating the electromagnet 1 and the armature 2. The
electromagnet 1 is fixed to the housing 3. In other words,
the present embodiment is directed to the electromagnetic
relay 100 in which the movable contact point 51 is operated
in response to the rotation of the armature 2. In the
following description, the upper, lower, left and right
sides will be defined on the basis of Fig. 1. The front
side of the drawing sheet in Fig. 1 will be called "front"
and the back side of the drawing sheet in Fig. 1 will be
called "rear". However, these directions are defined just
for the sake of convenience in description and may not
conform to the directions under an actual use condition.
The housing 3 includes a body 31 having a storage
recess 30 whose front side is opened and a cover (not shown)
coupled to the front side of the body 31 to close the
storage recess 30.
The electromagnetic relay 100 includes a support body
4 for rotatably supporting the armature 2 with respect to
the housing 3. The support body 4 includes a flat fixing
portion 41 whose thickness direction extends in the front-
rear direction and whose left-right end portions are fixed
to the body 31 and a cylindrical columnar shaft portion 42
protruding frontward from a central area of a front surface
of the fixing portion 41. The axial direction of the shaft
portion 4 2 extends in the front-rear direction. As a means
for fixing the fixing portion 41 to the body 31, it is
possible to use a well-known means such as fitting or the
like. The armature 2 has a bearing hole 20 with a circular
cross section. The bearing hole 2 0 extends through the
armature 2 in the front-rear direction. The inner diameter
of the bearing hole 2 0 is a little larger than the outer
diameter of the shaft portion 42. The shaft portion 4 2 is
inserted into the bearing hole 20, whereby the armature 2 is
supported with respect to the housing 3 so as to rotate
about the center axis of the shaft portion 42.
The electromagnet 1 includes a coil {not shown) fixed
to the body 31 at the rear side of the fixing portion 41
such that the axial direction thereof extends in the up-down
direction and a magnetic pole piece 11 made of a magnetic
material and magnetized by the coil. The magnetic pole
piece 11 includes a body portion {not shown) extending
through the coil in the up-down direction and variable
magnetic pole portions 11a protruding frontward from the
upper and lower ends of the body portion. Thus, the
magnetic pole piece 11 has a substantially U-like shape as a
whole. More specifically, the variable magnetic pole
portions 11a are magnetized into different polarities
depending on the flow direction of an electric current
supplied to the coil. The polarities of the variable
magnetic pole portions 11a differ from each other. A
plurality of (three, in Fig. 1) coil terminals 60 are held
in the housing 3. The coil terminals 60 are electrically
connected to the coil at one ends thereof. The other ends
of the coil terminals 60 protrude toward the left side of
the housing 3. An electric current is fed to the coil
through the coil terminals 60. More specifically, the
electromagnetic relay 100 according to the present
embodiment is of a so-called two-coil latch type. The coil
is provided with a tap. The coil terminals 60 are
electrically connected to the opposite ends and the tap of
the coil.
The armature 2 includes two pairs of fixed magnetic
pole portions 21a, which are respectively provided at the
upper and lower end portions thereof. Each of the variable
magnetic pole portions 11a is interposed between each pair
of the fixed magnetic pole portions 21a. In each pair of
the fixed magnetic pole portions 21a, the fixed magnetic
pole portion 21a existing at the left side of the variable
magnetic pole portions 11a and the fixed magnetic pole
portion 21a existing at the right side of the variable
magnetic pole portions 11a are magnetized with different
polarities. More specifically, the armature 2 includes two
permanent magnets 22 whose N-poles are oriented in the same
left or right direction, two armature members 21 made of a
magnetic material and a synthetic-resin molded body 23 with
which the permanent magnets 22 and the armature members 21
are insert-molded. Each of the armature members 21 is
magnetically attached to the pole of each of the permanent
magnets 2 2. The opposite end portions of each of the
armature members 21 protruding upward and downward beyond
each of the permanent magnets 22 serve as the fixed magnetic
pole portions 21a.
If an electric current is supplied to the coil of the
electromagnet 1, one of the fixed magnetic pole portions 21a
existing at the left and right sides of the corresponding
variable magnetic pole portion 11a is attracted to the
corresponding variable magnetic pole portion 11a depending
on the direction of the electric current flowing through the
coil, whereby the armature 2 is rotated with respect to the
housing 3. Once the electric current is supplied to the
coil, the position of the armature 2 (and the position of
the movable contact point 51 moving together with the
armature 2) is maintained (latched) by the magnetic force of
the permanent magnets 22 until an electric current flows
through the coil in the reverse direction.
A movable contact point 51 moving together with the
rotation of the armature 2 and a fixed contact point 52
coming into contact with or out of contact with the movable
contact point 51 are stored within the housing 3. The
movable contact point 51 and the fixed contact point 52 are
electrically connected to terminal plates 61 and 62,
respectively. In other words, the electric connection
between the terminal plates 61 and 62 is switched on and off
as the movable contact point 51 comes into contact with or
out of contact with the movable contact point 51. Each of
the terminal plates 61 and 62 is formed of a metal plate
with the thickness direction thereof extending in the left-
right direction. Each of the terminal plates 61 and 62 is
fixed to the housing 3 in such a fashion that the upper end
portion thereof protrudes outside the housing 3. The
electromagnetic relay 100 according to the present
embodiment includes a contact point retainer 7. The lower
end portion of the contact point retainer 7 is fixed to a
right surface of the terminal plate 61 and the upper end
portion of the contact point retainer 7 is elastically
deformable to be displaced in the left-right direction with
respect to the lower end portion of the contact point
retainer 7 . In other words, the movable contact point 51,
the fixed contact point 52, the contact point retainer 7 and
the housing 3 make up a contact device. The movable contact
point 51 is fixed to the upper end portion of the contact
point retainer 7, so that the movable contact point 51 can
be elastically displaced in the left-right direction with
respect to the housing 3 at the left side of the fixed
contact point 52.
The electromagnetic relay 100 according to the present
embodiment includes a card 8 connected to the contact point
retainer 7 and the armature 2 so that the movable contact
point 51 can move together with the armature 2. The
terminal plate 61 connected to the movable contact point 51
is shaped not to interfere with the moving path of the card
8 so that the terminal plate 61 should not hinder the
displacement of the card 8. The armature 2 and the card 8
are connected to each other by inserting the connector piece
24 connected to the upper end portion of the right armature
member 21 of the armature 2 into an armature recess portion
81 of the card 8 opened upward, downward and frontward. The
contact point retainer 7 and the card 8 are connected to
each other by inserting the upper end portion of the contact
point retainer 7 into a recess portion (not shown) of the
card 8 opened upward, downward and rearward.
The contact point retainer 7 includes a plurality of
contact point retaining springs 71, each of which is formed
of a leaf spring extending in the up-down direction. The
contact point retaining springs 71 are superimposed in the
thickness direction and are bonded to one another at the
upper end portions and the lower end portions thereof. Each
of the contact point retaining springs 71 includes a bulging
portion 71a swelling rightward (namely, in a parallel or
substantially parallel direction to the direction from the
movable contact point 51 toward the fixed contact point 52).
The bulging portion 71a is formed in a substantially central
portion of each of the contact point retaining springs 71 in
the up-down direction. The upper and lower end portions of
each of the contact point retaining springs 71 existing
above and below the bulging portion 71a are flat with the
thickness direction thereof extending in the left-right
direction. The bulging portion 71a is formed by a bending
work. The bulging portion 71a has, e.g., a trapezoidal
shape, and includes three flat sections connected to one
another through bent sections bent at an obtuse angle. The
bulging portions 71a of the contact point retaining springs
71 are formed into a box-like shape so that the bulging
portion 71a of the left contact point retaining spring 71
can be received in the left recess of the bulging portion
71a of the right left contact point retaining spring 71.
Gaps exist between the adjoining bulging portions 71a of the
contact point retaining springs 71. In particular, the gap
existing between the bulging portion 71a of the leftmost
contact point retaining spring 71 and the bulging portion
71a of the contact point retaining spring 71 adjoining to
the leftmost contact point retaining spring 71 is formed
into a relatively large size.
With the configuration described above, upon supplying
a large current, electric currents flow through the upper
end section and the lower end section of the bulging portion
71a in the substantially opposite directions, whereby a
repulsion force is generated between upper end section and
the lower end section of the bulging portion 71a as
indicated by arrows Al. The repulsion force acts to deform
the contact point retainer 7 in such a direction that the
upper end portion of the contact point retainer 7 is
displaced rightward with respect to the lower end portion
thereof as indicated by an arrow A2, namely in such a
direction that the movable contact point 51 is pressed
against the fixed contact point 52. This makes it possible
to restrain disconnection of the contact points.
Since the gaps exist between the contact point
retaining springs 71 (between the bulging portions 71a), the
operation characteristics can be adjusted by plastically
deforming the respective contact point retaining springs 71
(e.g., the leftmost contact point retaining spring 71) in an
appropriate manner.
It is more preferable to form the bulging portion 71a
into a shape (e.g., a rectangular shape) in which the upper
and lower sections thereof extend parallel to each other,
than to form the bulging portion 71a into the trapezoidal
shape described above. In that case, the electric currents
flow through the upper and lower sections of bulging portion
71a in the perfectly opposite directions and the repulsion
force becomes stronger.
The bulging portion 71a is positioned near the
terminal plate 62. Preferably, the distance between the
terminal plate 62 existing at the side of the fixed contact
point 52 and the bulging portion 71a is set as small as
possible insofar as the insulation can be secured. For
example, if the size of the bulging portion 71a is made
larger, it becomes possible to make the contact point
retaining springs 71 longer. If the position of the
terminal plate 62 is set closer to the contact point
retainer 7, it becomes possible to reduce the overall size
of the electromagnetic relay 100.
While the invention has been shown and described with
respect to the embodiments, the present invention is not
limited thereto. It will be understood by those skilled in
the art that various changes and modifications may be made
without departing from the scope of the invention as defined
in the following claims.
We Claim :
1. A contact device, comprising:
a contact point retainer configured to hold a movable
contact point in one end portion thereof, the contact point
retainer including a plurality of contact point retaining
springs superimposed in a thickness direction and formed of
leaf springs; and
a housing configured to fix the other end portion of
the contact point retainer and hold a fixed contact point in
a position wnere the movable contact point can come into
contact with or out of contact with the fixed contact point
in response to elastic deformation of the contact point
retainer,
wherein each of the contact point retaining springs
includes a bulging portion swelling away in a direction
parallel or substantially parallel to a direction from the
movable contact point and toward the fixed contact point.
2. The device of claim 1, wherein a gap exist between the
bulging portion of at last one of the contact point
retaining springs and the bulging portion of the contact
point retaining spring adjoining to said at least one of the
contact point retaining springs.
3. The device of claim 1 or 2, wherein the bulging portion
includes a plurality of flat sections connected to one
another through angularly bent sections.
4 . The device of claim 3, wherein the bulging portion
includes upper and lower sections extending parallel to each
other.
5. The device of any one of claims 1 to 4, further
comprising:
a terminal plate electrically connected to the fixed
contact point and held in the housing in such a fashion as
to partially protrude outside the housing, the bulging
portion positioned near the terminal plate.
6. An electromagnetic relay, comprising:
the contact device of any one of claims 1 to 5;
an electromagnet stored and held within the housing;
and
an armature stored within the housing and driven by a
magnetic force of the electromagnet,
wherein the movable contact point is configured to move
together with the armature and to come into contact with or
out of contact with the fixed contact point.
Dated this 18th day of July, 2012.

ABSTRACT

A contact device includes a contact point retainer configured to hold a movable contact point in one end portion thereof. The contact point retainer includes a plurality of contact point retaining springs superimposed in a thickness direction and formed of leaf springs and a housing configured to fix the other end portion of the contact point retainer and hold a fixed contact point in a position where the movable contact point can come into contact with or out of contact with the fixed contact point
in response to elastic deformation of the contact point retainer. Each of the contact point retaining springs includes a bulging portion swelling away in a direction parallel or substantially parallel to a direction from the
movable contact point and toward the fixed contact point.